Hard-Decision Coded Modulation for High-Throughput Short-Reach Optical Interconnect

Area of Science:

• Optical Communications
• Digital Signal Processing

Background:

• Coded modulation (CM) is crucial for optical systems, but designing low-complexity, high-rate schemes remains challenging.
• Existing CM systems face limitations in balancing coding gain, shaping gain, and complexity for applications like data center interconnects.

Purpose of the Study:

• To propose a novel CM scheme that jointly optimizes coding and shaping gains with low complexity.
• To address the stringent requirements of high data rates, low latency, and low overhead in optical communication systems.

Main Methods:

• Combining a soft-aided bit-marking decoding algorithm for staircase codes (SCCs) with geometrically-shaped constellations.
• Utilizing bit-wise hard-decision forward error correction (FEC) and geometric shaping for enhanced performance.

Main Results:

• Achieved up to 0.83 dB improvement at a 10^-6 bit error rate in AWGN channels compared to existing CM systems.
• Demonstrated up to a 24% increase in transmission reach for nonlinear optical fiber systems.
• Enabled rate adaptivity with six data rates ranging from 450 Gbit/s to 666 Gbit/s.

Conclusions:

• The proposed CM scheme effectively boosts coding and shaping gains while maintaining low complexity.
• This approach offers significant performance improvements and flexibility for future optical communication systems.